Lever locks have been developed over several hundred years. When used with corresponding keys, and with an appropriate selection of levers, very many combinations may be achieved.
As these locks have developed, so have techniques to pick or disable the locks. For example, locksmiths (and thieves) have access to picking tools which may be used to move levers one at a time past the gating stump so that the bolt may be withdrawn. Another technique, which is used by locksmiths, is to drill into a lock to remove the gating stump. Yet another technique is to force a flat tool into the lock between the bolt and the socket. The bolt may then be levered back or bent to such an extent that the door may be opened.
If wall safes are considered, locks may be fitted at the right side of a door, its left side or at its bottom or top. It is necessary, therefore, for a locksmith to carry several different types of lock to suit left-handed or right-handed persons.
It is an object of the present invention to make the unauthorised opening of locks significantly more difficult.
It is another object of the invention to provide a lock which may be used at a variety of locations on a door.
It is yet another object of the invention to provide a lock which may be used to lock into the tail bar of the main locking bolt for a bank safe, strong-room or vault.
It is a further object of this invention to provide a lock which may be used domestically, for example, a mortice lock.